Water heater pilot light goes out

I have a Reliance 606 water heater that the pilot light goes out frequently, actually every day. A plumber friend told me that the thermocouple had gone bad, he then proceeded to place a fan in front of the unit and that has worked ever since.

I really don't want the fan running all of the time, which it must be, and would like to repair the water heater permanently. The unit is not under warranty. Any suggestions?

If the thermocouple is bad, the heater will not light in the first place, regardless of whether you have a fan there or not. You have a different problem, and if a fan cures it, it could be a combustion venting problem, and that is worse than a bad thermocouple, because it can kill you.